The ongoing nuclear crisis in Japan has sparked renewed debate around the world about the safety of nuclear power.

The earthquake and tsunami in Japan devastated the island nation. Thousands are dead. Whole communities washed away. Now a new danger looms: nuclear meltdown.

Many Japanese are panicked. "Nobody is telling us, the citizens, what is really happening," one Japanese said.

What, by most accounts, has happened is this: Multiple reactors at the Fukushima Daiichi nuclear power plant have malfunctioned, with radiation leaking as a result.

Japan’s prime minister said on national television that radiation levels seem very high, and Japan’s chief government spokesman added this:

"Now we are talking about levels that can impact human health," said cabinet secretary Yukio Edano.

Government authorities urged those close to the reactor sites to stay indoors.

As this new nightmare unfolds in Japan, nuclear industry representatives and government officials in the U.S. are offering assurances that nuclear power is safe.

"The American people should have full confidence that the U.S. has rigorous safety regulations in place to ensure that our nuclear power is generated safely and responsibly," said U.S. Energy Secretary Steven Chu.

But industry watchdogs say that simply is not so. They concede safety has improved at nuclear power plants in recent years, but they say Americans still should prepare for the worst.

"Obviously the Japanese, the most prepared for earthquakes and tsunamis than any country in the world, underestimated the potential of a 9.0 earthquake. Obviously there has to be a reappraisal of safety risks," said Kevin Kamps of the radioactive waste watchdog group

Beyond Nuclear. Kamps opposes license extensions at more than 20 nuclear power plants in the U.S.

"Fukushima Unit One at the Daiichi Plant was a 40-year reactor. It was the first one to go into crisis. We have 23 reactors in the United States of the very same design," he said.

And Arjun Makhijani of the Institute for Energy and Environmental Research wants a thorough re-evaluation of U.S. nuclear power plants in coastal areas and along seismic fault lines. He also wants to know who will pay for a clearnup if a nuclear disaster occurs."

"The nuclear industry is not required to even cover more than $11 billion in costs, and at a time when we are saying how are we going to minimize government exposure and so on this is an item that should be put back on the table," Makhijani said.

Makhijani says it could cost hundreds of billions of dollars. He would like to see nuclear energy phased out over time.

"Making plutonium and fission products which last for tens of thousands of years or millions of years just to boil water isn’t sensible. We can do it much better. We can do it more cleanly," Makhijani said.

Since the earthquake and tsunami in Japan, authorities have scrambled to cool the core of those reactors with sea water. But the water appears to be evaporating more quickly than it can be pumped in.